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Subject: Re: [PATCH 3/6] remoteproc/pru: Add support for PRU specific
 interrupt configuration
To:     Grzegorz Jaszczyk <grzegorz.jaszczyk@linaro.org>
CC:     Ohad Ben Cohen <ohad@wizery.com>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Mathieu Poirier <mathieu.poirier@linaro.org>,
        <linux-remoteproc@vger.kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Lee Jones <lee.jones@linaro.org>, <devicetree@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <linux-omap@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        "Bajjuri, Praneeth" <praneeth@ti.com>,
        Roger Quadros <rogerq@ti.com>
References: <20201114084613.13503-1-grzegorz.jaszczyk@linaro.org>
 <20201114084613.13503-4-grzegorz.jaszczyk@linaro.org>
 <5e92947a-febf-90d0-b40e-499fe2144737@ti.com>
 <CAMxfBF5xMyb4LZ6Ei9xS49yXfHWJjKppWo7NNHqc5CfHYAiZTg@mail.gmail.com>
From:   Suman Anna <s-anna@ti.com>
Message-ID: <ada369ed-0c1b-46e1-68bb-b37d04cf90fd@ti.com>
Date:   Wed, 18 Nov 2020 17:04:04 -0600
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Hi Greg,

On 11/18/20 9:27 AM, Grzegorz Jaszczyk wrote:
> Hi Suman,
> 
> On Tue, 17 Nov 2020 at 21:40, Suman Anna <s-anna@ti.com> wrote:
>>
>> Hi Greg,
>>
>> On 11/14/20 2:46 AM, Grzegorz Jaszczyk wrote:
>>> The firmware blob can contain optional ELF sections: .resource_table
>>> section and .pru_irq_map one. The second one contains the PRUSS
>>> interrupt mapping description, which needs to be setup before powering
>>> on the PRU core. To avoid RAM wastage this ELF section is not mapped to
>>> any ELF segment (by the firmware linker) and therefore is not loaded to
>>> PRU memory.
>>>
>>> The PRU interrupt configuration is handled within the PRUSS INTC irqchip
>>> driver and leverages the system events to interrupt channels and host
>>> interrupts mapping configuration. Relevant irq routing information is
>>> passed through a special .pru_irq_map ELF section (for interrupts routed
>>> to and used by PRU cores) or via the PRU application's device tree node
>>> (for interrupts routed to and used by the main CPU). The mappings are
>>> currently programmed during the booting/shutdown of the PRU.
>>>
>>> The interrupt configuration passed through .pru_irq_map ELF section is
>>> optional. It varies on specific firmware functionality and therefore
>>> have to be unwinded during PRU stop and performed again during
>>> PRU start.
>>>
>>> Co-developed-by: Suman Anna <s-anna@ti.com>
>>> Signed-off-by: Suman Anna <s-anna@ti.com>
>>> Signed-off-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@linaro.org>
>>> ---
>>>  drivers/remoteproc/pru_rproc.c | 191 ++++++++++++++++++++++++++++++++-
>>>  drivers/remoteproc/pru_rproc.h |  46 ++++++++
>>>  2 files changed, 236 insertions(+), 1 deletion(-)
>>>  create mode 100644 drivers/remoteproc/pru_rproc.h
>>>
>>> diff --git a/drivers/remoteproc/pru_rproc.c b/drivers/remoteproc/pru_rproc.c
>>> index c94c8e965c21..825e9c7e081b 100644
>>> --- a/drivers/remoteproc/pru_rproc.c
>>> +++ b/drivers/remoteproc/pru_rproc.c
>>> @@ -11,13 +11,16 @@
>>>   */
>>>
>>>  #include <linux/bitops.h>
>>> +#include <linux/irqdomain.h>
>>>  #include <linux/module.h>
>>>  #include <linux/of_device.h>
>>> +#include <linux/of_irq.h>
>>>  #include <linux/pruss_driver.h>
>>>  #include <linux/remoteproc.h>
>>>
>>>  #include "remoteproc_internal.h"
>>>  #include "remoteproc_elf_helpers.h"
>>> +#include "pru_rproc.h"
>>>
>>>  /* PRU_ICSS_PRU_CTRL registers */
>>>  #define PRU_CTRL_CTRL                0x0000
>>> @@ -41,6 +44,8 @@
>>>  #define PRU_SDRAM_DA 0x2000  /* Secondary Data RAM */
>>>  #define PRU_SHRDRAM_DA       0x10000 /* Shared Data RAM */
>>>
>>> +#define MAX_PRU_SYS_EVENTS 160
>>> +
>>>  /**
>>>   * enum pru_iomem - PRU core memory/register range identifiers
>>>   *
>>> @@ -64,6 +69,10 @@ enum pru_iomem {
>>>   * @rproc: remoteproc pointer for this PRU core
>>>   * @mem_regions: data for each of the PRU memory regions
>>>   * @fw_name: name of firmware image used during loading
>>> + * @mapped_irq: virtual interrupt numbers of created fw specific mapping
>>> + * @pru_interrupt_map: pointer to interrupt mapping description (firmware)
>>> + * @pru_interrupt_map_sz: pru_interrupt_map size
>>> + * @evt_count: number of mapped events
>>>   */
>>>  struct pru_rproc {
>>>       int id;
>>> @@ -72,6 +81,10 @@ struct pru_rproc {
>>>       struct rproc *rproc;
>>>       struct pruss_mem_region mem_regions[PRU_IOMEM_MAX];
>>>       const char *fw_name;
>>> +     int *mapped_irq;
>>> +     struct pru_irq_rsc *pru_interrupt_map;
>>> +     size_t pru_interrupt_map_sz;
>>> +     ssize_t evt_count;
>>
>> Do you really need this to be ssize_t type?
> 
> You are right, it is not needed. I will use size_t type instead and
> modify relevant while loop.

Hmm, size_t is ok, but perhaps the same type you used struct pru_irq_rsc is better.

> 
>>
>>>  };
>>>
>>>  static inline u32 pru_control_read_reg(struct pru_rproc *pru, unsigned int reg)
>>> @@ -85,15 +98,107 @@ void pru_control_write_reg(struct pru_rproc *pru, unsigned int reg, u32 val)
>>>       writel_relaxed(val, pru->mem_regions[PRU_IOMEM_CTRL].va + reg);
>>>  }
>>>
>>> +static void pru_dispose_irq_mapping(struct pru_rproc *pru)
>>> +{
>>> +     while (--pru->evt_count >= 0) {
>>> +             if (pru->mapped_irq[pru->evt_count] > 0)
>>> +                     irq_dispose_mapping(pru->mapped_irq[pru->evt_count]);
>>> +     }
>>> +
>>> +     kfree(pru->mapped_irq);
>>> +}
>>> +
>>> +/*
>>> + * Parse the custom PRU interrupt map resource and configure the INTC
>>> + * appropriately.
>>> + */
>>> +static int pru_handle_intrmap(struct rproc *rproc)
>>> +{
>>> +     struct device *dev = rproc->dev.parent;
>>> +     struct pru_rproc *pru = rproc->priv;
>>> +     struct pru_irq_rsc *rsc = pru->pru_interrupt_map;
>>> +     struct irq_fwspec fwspec;
>>> +     struct device_node *irq_parent;
>>> +     int i, ret = 0;
>>> +
>>> +     /* not having pru_interrupt_map is not an error */
>>> +     if (!rsc)
>>> +             return 0;
>>> +
>>> +     /* currently supporting only type 0 */
>>> +     if (rsc->type != 0) {
>>> +             dev_err(dev, "unsupported rsc type: %d\n", rsc->type);
>>> +             return -EINVAL;
>>> +     }
>>> +
>>> +     if (rsc->num_evts < 0 || rsc->num_evts > MAX_PRU_SYS_EVENTS)
>>> +             return -EINVAL;
>>> +
>>> +     if (sizeof(*rsc) + rsc->num_evts * sizeof(struct pruss_int_map) !=
>>> +         pru->pru_interrupt_map_sz)
>>> +             return -EINVAL;
>>> +
>>> +     pru->evt_count = rsc->num_evts;
>>> +     pru->mapped_irq = kcalloc(pru->evt_count, sizeof(int), GFP_KERNEL);
>>> +     if (!pru->mapped_irq)
>>> +             return -ENOMEM;
>>> +
>>> +     /*
>>> +      * parse and fill in system event to interrupt channel and
>>> +      * channel-to-host mapping
>>> +      */
>>> +     irq_parent = of_irq_find_parent(pru->dev->of_node);
>>> +     if (!irq_parent) {
>>> +             kfree(pru->mapped_irq);
>>> +             return -ENODEV;
>>> +     }
>>> +
>>> +     fwspec.fwnode = of_node_to_fwnode(irq_parent);
>>> +     fwspec.param_count = 3;
>>> +     for (i = 0; i < pru->evt_count; i++) {
>>> +             fwspec.param[0] = rsc->pru_intc_map[i].event;
>>> +             fwspec.param[1] = rsc->pru_intc_map[i].chnl;
>>> +             fwspec.param[2] = rsc->pru_intc_map[i].host;
>>> +
>>> +             dev_dbg(dev, "mapping%d: event %d, chnl %d, host %d\n",
>>> +                    i, fwspec.param[0], fwspec.param[1], fwspec.param[2]);
>>> +
>>> +             pru->mapped_irq[i] = irq_create_fwspec_mapping(&fwspec);
>>> +             if (pru->mapped_irq[i] < 0) {
>>> +                     dev_err(dev, "failed to get virq\n");
>>> +                     ret = pru->mapped_irq[i];
>>> +                     goto map_fail;
>>> +             }
>>> +     }
>>> +
>>> +     return ret;
>>> +
>>> +map_fail:
>>> +     pru_dispose_irq_mapping(pru);
>>> +
>>> +     return ret;
>>> +}
>>> +
>>>  static int pru_rproc_start(struct rproc *rproc)
>>>  {
>>>       struct device *dev = &rproc->dev;
>>>       struct pru_rproc *pru = rproc->priv;
>>>       u32 val;
>>> +     int ret;
>>>
>>>       dev_dbg(dev, "starting PRU%d: entry-point = 0x%llx\n",
>>>               pru->id, (rproc->bootaddr >> 2));
>>>
>>> +     ret = pru_handle_intrmap(rproc);
>>> +     /*
>>> +      * reset references to pru interrupt map - they will stop being valid
>>> +      * after rproc_start returns
>>> +      */
>>> +     pru->pru_interrupt_map = NULL;
>>> +     pru->pru_interrupt_map_sz = 0;
>>> +     if (ret)
>>> +             return ret;
>>> +
>>>       val = CTRL_CTRL_EN | ((rproc->bootaddr >> 2) << 16);
>>>       pru_control_write_reg(pru, PRU_CTRL_CTRL, val);
>>>
>>> @@ -112,6 +217,10 @@ static int pru_rproc_stop(struct rproc *rproc)
>>>       val &= ~CTRL_CTRL_EN;
>>>       pru_control_write_reg(pru, PRU_CTRL_CTRL, val);
>>>
>>> +     /* dispose irq mapping - new firmware can provide new mapping */
>>> +     if (pru->mapped_irq)
>>> +             pru_dispose_irq_mapping(pru);
>>> +
>>>       return 0;
>>>  }
>>>
>>> @@ -274,16 +383,96 @@ pru_rproc_load_elf_segments(struct rproc *rproc, const struct firmware *fw)
>>>       return ret;
>>>  }
>>>
>>> +static const void *
>>> +pru_rproc_find_interrupt_map(struct device *dev, const struct firmware *fw)
>>> +{
>>> +     const void *shdr, *name_table_shdr;
>>> +     const char *name_table;
>>> +     const u8 *elf_data = (void *)fw->data;
>>> +     u8 class = fw_elf_get_class(fw);
>>> +     size_t fw_size = fw->size;
>>> +     const void *ehdr = elf_data;
>>> +     u16 shnum = elf_hdr_get_e_shnum(class, ehdr);
>>> +     u32 elf_shdr_get_size = elf_size_of_shdr(class);
>>> +     u16 shstrndx = elf_hdr_get_e_shstrndx(class, ehdr);
>>> +     int i;
>>> +
>>> +     /* first, get the section header according to the elf class */
>>> +     shdr = elf_data + elf_hdr_get_e_shoff(class, ehdr);
>>> +     /* compute name table section header entry in shdr array */
>>> +     name_table_shdr = shdr + (shstrndx * elf_shdr_get_size);
>>> +     /* finally, compute the name table section address in elf */
>>> +     name_table = elf_data + elf_shdr_get_sh_offset(class, name_table_shdr);
>>
>> I see you used the style influenced by the remoteproc_elf_loader code. PRUs are
>> all 32-bit, so we need not use this strictly. I am ok with this style, but
>> prefer consistent usage style between this function and
>> pru_rproc_load_elf_segments().
> 
> Ok. I will get rid of generic elf helpers macros usage and will stick
> with elf32_* related structs instead. This will make it similar to
> pru_rproc_load_elf_segments() in terms of style.

Yeah, ok with me.

> 
>>
>>> +
>>> +     for (i = 0; i < shnum; i++, shdr += elf_shdr_get_size) {
>>> +             u64 size = elf_shdr_get_sh_size(class, shdr);
>>> +             u64 offset = elf_shdr_get_sh_offset(class, shdr);
>>> +             u32 name = elf_shdr_get_sh_name(class, shdr);
>>> +
>>> +             if (strcmp(name_table + name, ".pru_irq_map"))
>>> +                     continue;
>>> +
>>> +             /* make sure we have the entire table */
>>> +             if (offset + size > fw_size || offset + size < size) {
>>> +                     dev_err(dev, "interrupt map sec truncated\n");
>>
>> sec can confuse developers, suggest rephrasing this trace, something like
>> ".pru_irq_map section truncated"
> 
> Ok. I will also update the comment to: "make sure we have the entire irq map"

Please don't use "we" in debug traces, and just the summary of the error trace.

> 
>>
>>> +                     return ERR_PTR(-EINVAL);
>>> +             }
>>> +
>>> +             /* make sure table has at least the header */
>>> +             if (sizeof(struct pru_irq_rsc) > size) {
>>> +                     dev_err(dev, "header-less interrupt map sec\n");
>>
>> same comment as above
> 
> Sure, I will use "header-less .pru_irq_map section\n" and update the
> comment above to: "make sure irq map has at least the header"

similar to above

> 
>>
>>> +                     return ERR_PTR(-EINVAL);
>>> +             }
>>> +
>>> +             return shdr;
>>> +     }
>>> +
>>> +     dev_dbg(dev, "no .pru_irq_map section found for this fw\n");
>>> +
>>> +     return NULL;
>>> +}
>>> +
>>> +/*
>>> + * Usa a custom parse_fw callback function for dealing with standard
>>> + * resource table and a PRU-specific custom ELF section.
>>> + *
>>> + * The firmware blob can contain optional ELF sections: .resource_table section
>>> + * and .pru_irq_map one. The second one contains the PRUSS interrupt mapping
>>> + * description, which needs to be setup before powering on the PRU core. To
>>> + * avoid RAM wastage this ELF section is not mapped to any ELF segment (by the
>>> + * firmware linker) and therefore is not loaded to PRU memory.
>>
>> Some of this description can move to Patch 2 as well.
> 
> I thought about it before posting but IMO this function without
> .pru_irq_map handling is kind of self explaining. Especially when
> taking into account comment and deb_dbg message from the function body
> of previous patch. Nevertheless I can add:
> /*
>  * Usa a custom parse_fw callback function for dealing with optional resource
>  * table.
>  */

Or you can keep the first two lines generic, "... dealing with PRU firmware
specific sections", and only add the details in the second paragraph in this
patch. The commit in code above resource table + these two links should suffice
for patch 2.

> 
> to patch #2 and then overwrite it in patch #3, but not sure if it is
> the best option.
> 
>>
>>> + */
>>>  static int pru_rproc_parse_fw(struct rproc *rproc, const struct firmware *fw)
>>>  {
>>> +     struct device *dev = &rproc->dev;
>>> +     struct pru_rproc *pru = rproc->priv;
>>> +     const u8 *elf_data = fw->data;
>>> +     const void *shdr;
>>> +     u8 class = fw_elf_get_class(fw);
>>> +     u64 sh_offset;
>>>       int ret;
>>>
>>>       /* load optional rsc table */
>>>       ret = rproc_elf_load_rsc_table(rproc, fw);
>>>       if (ret == -EINVAL)
>>>               dev_dbg(&rproc->dev, "no resource table found for this fw\n");
>>> +     else if (ret)
>>> +             return ret;
>>
>> This hunk should be part of Patch 2.
> 
> You are right.
> 
>>
>>>
>>> -     return ret;
>>> +     /* find .pru_interrupt_map section, not having it is not an error */
>>> +     shdr = pru_rproc_find_interrupt_map(dev, fw);
>>> +     if (IS_ERR(shdr))
>>> +             return PTR_ERR(shdr);
>>> +
>>> +     if (!shdr)
>>> +             return 0;
>>> +
>>> +     /* preserve pointer to PRU interrupt map together with it size */
>>> +     sh_offset = elf_shdr_get_sh_offset(class, shdr);
>>> +     pru->pru_interrupt_map = (struct pru_irq_rsc *)(elf_data + sh_offset);
>>> +     pru->pru_interrupt_map_sz = elf_shdr_get_sh_size(class, shdr);
>>> +
>>> +     return 0;
>>
>> And this one as well.
> 
> Correct,
> 
> Thank you for your review,
> Grzegorz

regards
Suman